New findings on light corona patients
A small study found that mild patients probably contract mainly in the first week of onset, and there may be different populations of healthy viruses and upper respiratory tract
Corona epidemic COVID-19 Caused by a virus we had not previously known. The new virus is a family member of the SARS virus that caused the plague in 2003 and the MERS virus that caused the plague at the beginning of the previous decade. The virus is also a family member of a number of viruses that cause colds or mild pneumonia. In recent months many studies have been published on how The virus culture andIts distribution in the population, But still hidden on the visible. It is still unclear where the body of the virus reproduces, how long it reproduces – especially in mild patients with little or no symptoms – and when the body begins to develop antibodies against the virus.
Research in Germany Followed nine minor patients since the onset of symptoms for 28 days. The symptoms of the mild patients included fever, loss of sensation and taste, cough And diarrhea. The researchers did PCR testing Daily nasal / pharyngeal surface, mucus samples (which represent lung cell adhesion), feces, blood and urine. The researchers found that the blood and urine were free of the virus – which indicates that the virus – at least in minor cases – does not penetrate the bloodstream. The genetic material of the virus is found on the nasal surface, in the phlegm and fecal samples. The researchers also searched other corona viruses, influenza viruses and other viruses) and found no co-infection – meaning all patients were really COVID-19 patients only.
The symptoms of the disease began to disappear after five days, and at the same time, the virus level decreased in all tests. In six out of nine patients, however, the virus is found up to three weeks after the onset of symptoms, mainly in phlegm and fecal samples and less in nasal or pharyngeal swab specimens. The researchers note that the virus is detected earlier and at a thousand-fold higher concentration than tests done at the time for the SARS virus, namely the new corona virus, SARS-CoV-2, is indeed more contagious.
To check when patients stop infecting, the researchers looked at whether a virus culture could be grown from the samples. While in the first week of symptoms, live viruses could be isolated in about 17 percent of the marker samples and 83 percent of the mucus tests, but from the eighth day researchers were unable to isolate live viruses even though the PCR tests were positive and indicated a high presence of the virus. At no point were researchers able to isolate live viruses from faecal samples. These results indicate that mild patients can only infect for up to a week after symptoms appear, and only through secretions from the respiratory system, and not through feces or urine. Researchers are again comparing the results published on the SARS virus, so they have rarely been able to grow live viruses from the samples.
Researchers were unable to isolate live viruses from the eighth day on. Corona viral cell culture | Photo by Lovely Bird, Shutterstock
Upward viruses, downward viruses
The researchers asked which virus to reproduce. To that end, they have developed a PCR test that checks for the presence of the virus’s RNA molecules that are created only while it is replicated – a contrast to the standard PCR test that detects the presence of the virus’s genetic material in general. Phlegm samples showed the presence of these molecules until day 9-8 after the onset of symptoms, and the decrease in the level of molecules began only on day 11-10. The nasal and pharynx swab samples were found on day 5-4, and then completely disappeared. In the fecal samples, these molecules were not found at all. The researchers hypothesize that the virus multiplies in two major areas – upper airway epithelial cells and healthy epithelial cells.
This hypothesis was reinforced by an unexpected finding: When researchers compared the complete genetic sequence of the viruses in each patient, one of them found that the upper respiratory virus contains several mutations that differentiate it from the lower respiratory virus. That is, in each tissue the virus multiplies separately and there is no mixing of the virus between the tissues. This result has an effect not only on diagnosis; it may also affect drug response – a drug that affects one tissue may not necessarily affect another in a similar way.
Two weeks of antibodies
Finally, the researchers examined the presence of antibodies to the virus. Half of the patients showed antibodies within a week of the onset of symptoms. Two weeks after the onset of symptoms, all patients had antibodies. There was no correlation between the nature of the symptoms and the speed of their disappearance to the level of antibodies in the blood. However, the patient with the lowest antibody level was also the patient who secreted stool viruses for the longest time. These may be related, but because this is a single patient, it may also be a coincidence that does not indicate the mechanism of the disease.
It is important to remember that the study was conducted on only nine patients and no far-reaching conclusions can be drawn on the duration of the desired isolation of minor patients, or when they can be determined to be vaccinated. Only studies on hundreds and thousands of patients can be used by policymakers in making such decisions. In addition, these are only minor patients, and there is currently no information on the vaccination capabilities and development of the vaccine in severely ill patients on the one hand and in patients without symptoms at all on the other.